(1) Field of the invention
The present invention generally relates to a method for extracting features from characters which is applied to a character recognition system, and more particularly to a method for extracting features from an on-line handwritten character.
(2) Description of related art
In an on-line handwriting recognition system, when an operator writes a character on a digitizing tablet, the character (an on-line handwritten character) is recognized based on coordinate data output from the digitizing tablet. The on-line handwriting recognition system has been studied for a long time. However, since the on-line handwritten character can have various shapes, it is difficult to accurately recognize the on-line handwritten character.
A conventional on-line handwriting recognition method is disclosed, for example, in Yoko Suminaga, "On-line handwriting recognition for Kanji characters easing restrictions of writing, such as a restriction regarding simplified characters" (NIKKEI ELECTRONICS, 331, pp. 115-133, Dec. 5, 1983). In this conventional on-line handwriting recognition method, the on-line handwritten character which can have various shapes is recognized by use of many features describing shapes of characters. However, as these features are adhoc determined, there is a disadvantage in that it requires a great deal of labor to make a dictionary regarding character shapes. Further, although the on-line handwriting recognition method requires an effective and high speed matching process, in the conventional on-line handwriting recognition method, a dynamic programming in which complex calculations are carried out is used to distinguish many different shapes of a character from each other. In addition, in a case where characters are recognized by use of a structural technique, as the structural technique greatly depends on a writing stroke order of each character, there is a disadvantage in that it requires a large-scale dictionary to recognize characters which can have various shapes, such as Kanji characters.